Wax-containing compositions for the protection of various surfaces including automobiles, agricultural vehicles and construction equipment are known. Among these, wax-solvent dispersions are widely used. More recently, water-based compositions have been described. These contain wax modifiers, coalescent film-forming agents to assist processing of the wax components, anionic, cationic and amphoteric surfactants to stabilize oil-in-water emulsions and various additives to improve the hardness and durability of the coating once applied to the surface to be protected.
Problems with protective coating for metals, especially those primarily intended for long-term storage protection, have always existed. Prominent difficulties have been tackiness, poor water removability, sensitivity to water, objectionable odor, and where water-borne compositions are involved, limited high-temperature storage stability of the compositions themselves. In addition, the solvent-containing protective compositions require substantial evaporation of their solvents for the formation of wax barrier coats. Drawbacks of such solvent-type protective compositions include the health, safety and environmental concerns associated with the vapor emissions from the solvents used.
The limitations of conventional solvent-containing coating preparations are best illustrated in the marine industry where their use produces dangerous conditions for applicators and welders in the void and tank areas of ships and barges. Accumulation of vapors in these areas can cause sudden explosions. During welding, the risk of flash fires is high.
The more recent formulations, which have eliminated solvents from the composition, still rely on the use of wax modifiers, surfactants and film forming agents to maintain the desired characteristics of durability and uniform coating properties. Wax modifiers such as naphthenic or paraffinic oils require that the right proportions be used to avoid a coating which will either flow off (melt) if the amount is too large or become too brittle if the amount is too little. Film forming properties are also imparted with film coalescing agents like mineral spirits and ethylene glycol monopropyl ether.